Sound reproducing device



' March 8, 1932. M. NYSTROM SOUND REPRODUCING DEVICE Filed March 31, 1928 2 Sheets-Sheet 1 I w afi March 8, 1932. M; NYSTROM 1,848,139

SOUND REPRODUCING DEVICE Filed March 31, 1928 2 Sheets-Sheet 2 if This rapplication is pending application,

Patented Mar. 8, "1932 MARTIN NYSTROMQOFFGHICAGO, inmnoIs'nssmNoR,

B'Y Mnsun 'As'siiGuMEuTs; 'ro

unman :aEsEAR cn eo ronn rrou; or LoN'd' s n-Nn CITY, NEWY RK, A oonronn 192s. Seral A S'erial April 10,1926.

, 'My inventionrelatesi tode vices for repro- I ducing sound and" has a special relationto sound boxes for phonographs. V I,

An object of my inventionis to provide a device for securing a stylus bar .to a diaphragm of'a sound box which will be light and therefore of such. nature as to transmit all vibrationsto the diaphragm and which;

at the same time, will eliminate the possibility of the stylus bar tearing loose from thedia-v phragm or setting up undesirable vibrations therein. I 7

Another object of my invention is to provide a mounting for a stylus bar which will v permit movement of the stylus bar with the and which will autoleast possible restraint matically take up loosencss of parts so as to eliminate chattering, straining of the stylus and undesirablevibrations.

bar,

from the bearings of the phonograph stylus bar. i

A further object isto reduce the'friction in a phonograph stylus carrying bar without introducing loeseness in the bearings. V

Still another object is of a ball bearing stylus barin firm contact without introducing undesired friction.

Other advantages will. appear as the description proceeds. p I

Referring to the accompanying drawings. Fig. 1 represents an elevational'view of a sound box embodying the invention;

Fig. 2 is a sectional view taken substantial v ly on the lineII-II of Fig. 1;

Fig. 3 is an enlarged detail view partlyin elevation and partly in section of the connection between adiaphragm and astylus bar;" 7

connection Fig. 5 is an enlarged sectional view taken on the line V Vif Fig. 1;

Figs. 6 and? are enlarged detail news] Stillanother object of my nvention is to eliminate looseness, end-play and chatter}.

l .The washer to holdthe ball races very light in weight, andytherefore,

Fig. 4 is anenlarged sectional view of the nnfna opuc naymz the condition of a stylusbar afterthe shank ,is' welded to the'bo dy ofathe bar.

such as aluminum or magnesium Oran alloy of either of these. metals v ible outer portion 2 approximately .002 of an Figs. 9, 0am 1 1 are enlar'ged. ew. the stylus bar showing it immediately prior and having. a flexe26, sen nc. 101,196. m idurana this ncatmamea-narm 51,

i 8 an enlargedtdetail view to the assemblyof 'a suppbrti f h ft w m? "inchi'n thickness'and arigid central portion 3' offcon'ical shape approximately L004 of an inch in thickness. f tionis slightlyfiattened at its apex and has an opening therethrough, through which extends a rivet. ci'nposed of a light metalsuch V eitherlof these metals.

l fwhichengages thejinnerffa'ceof the dia .ph ragml and its outer end is countersunk in a washer. SQmadeofsuitable material such asbrass which i'slthus held. securely against thediapnmgm;

which receive forkedendsoii ashank 7 ofa stylus bar, the ends washer by means of: solder The described devices shank of the stylus bar to the diaphragm are promote the faithfulness of by the diaphragm; f are durable and remainin operative condition after prolonged usage "without dis- .ru tin'g the fragile diaphragm, without painthe acoustic effect... I

' Tlie shank of the stylus bar. is thin and is preferably made of hard metal such as spring steel, it is vwelded to a stylus 9 which is relatively heavy. i

The-stylus bar'jbodyhas a transverse bore extending therethrough in; which is secured diends wh :pr

a shaft 10- hav ng tapere whi pe m tt e, s yl i ibar o vi ratelfr ely The conical central per-.

for: securing the I asaluininum or magnesium or an alloy of The rivet has a head 5 s and l t t he-ah ban ,seeuredtoithe thereproduction of-fsound; I

'et at the same time they' any looseness developing which would im- 1 a bodyject laterally, gandarerecejived in bearings-ll i on thegsoundibox ,casing.-;I;Each endof;.,the' I shat-tie supported bya. series ,of. ba11s- 12 l.'

I in order that it may there can be no lost thereon, a stylus bar, a pair of taperediends received in said bear- To prevent the shaft from deteriorating through wear, it is made of a durable metal such as hard steel.

In eachbearing is a follower 13 which engages the balls and retains themin place, the followers are urged against the balls by means of a single spring which is provided projection 15 on the follower. The spring is mounted in grooves 16 on the outer face of the bearings and is as shown at 17 bowed ad-v jacent its ends and also between the bearings be especially resilient. By forcing the followers inwardly, the spring retains the balls in engagement with the bearings and the ends of the shaft. Thus motion in the pivotal movement of the'stylus bar and looseness of par-ts is automatically taken up.

In making the stylus bar, the shank? is with a depression 14 at each end to receive a spring engaging both of said followers and urging them against said balls, and releasable means for maintaing said spring in operative position with respect to said followers. r V

3. In amounting for a stylus bar, the combination of a sound box, a pair of bearings thereon, each having a .groove therein, a stylus bar, a pivottherefor having a pair of tapered ends received in said bearings, a plurality of.v balls surrounding each of said ends, a follower in each bearing for maintaining pressure'on the balls and holding them in operative position and a single leaf spring having a main body portion received n said grooves and having laterally directed ends engaging said followers and urging them against said balls.

MARTIN NYSTROM.

punched from sheets of metal and in its ini- I tialform is as shown in Figs. 6 and 7." The shank is then bent as shown at 18 and is twisted as shown at 19 so that the ends of the shank are in a line extending V perpendicularly to the plane of the main portion of the shank. The shank is then welded to a forging, through which a bore is then drilled, and in which a recess 20 is made toreceive a stylus 21. The shaft 10 is then forced into the bore and the stylus bar is ready for assembly with the sound box. The shaft is made separate from and not integral with the stylus bar body as it is necessary to harden the shaft and grind the ends thereof where they en- 'without departing from the spirit of the invention, and a substantial range of equivalents is contemplated within'the scope of the appended claims.

lVh'at I claim and ters Patent is: r

1. In a mounting for a stylus bar, the combination of a sound box, a pair of bearings thereon, .a stylus bar, a pivot therefor having a pair of tapered ends received in said bearings, a plurality of balls surrounding each of said ends, a follower in each bearing for maintaining pressure on the balls and holding them in operative position and a single spring engaging both of saidfollowers and urging them against said balls.

2. In a mounting or a stylus bar, the combination of a sound box, a pair of bearings a pivot'therefor having desire to secure by Letings, aplurality of'balls surrounding each of said ends, a ollower n each bear ng for gage the balls andit would be dillicult to perl I form the grinding operations if the shaft maintaining a pressure on the balls and hol'd- I mg them in operative position, a single 

